Upload & Sell: On
Here's my worst: Nikon 24mm f/2 AIS. This lens was BADLY abused, and I knew it when I bought it for about $49. The lenses was partially rebuild by Nikon (at no charge!), replacing the front lens barrel and elements -- the front element was nearly as scraped up, with a few deeper gouges. Unfortunately, the rear element group was not available (screws out in its own sheathed assembly). Nikon polished the rear element slightly (it looked much worse before). Aperture is nearly clickless, but accurate. Focusing is super smooth, although the rubber grip is terribly worn. Accurate viewfinder focusing is a bit tricky, but LV is great.
I can't sell it for anything, so I keep it. It is a genuine f/2.0, after all!
What are the results? f/2 to 2.8 are soft, sort of dreamy flare. f/4 to 5.6 is the best range and pretty sharp, but with reduced contrast (as you would expect). Beyond f/5.6, things go downhill as the very center of the rear element concentrates the light going through it and its marks. The lens excels in certain situations, and it certainly can't be killed!
Amazing what you can get out of a lens with surface imperfections. Kinda puts things in perspective for minor scratches and dust specks.
Photo taken at f/2.8.